vcpkg fetch fails with ninja

[Erik-White]

Describe the bug
Since the implementation of vcpkg fetch, builds are failing when attempting to use ninja:

Extracting cmake...
Detecting compiler hash for triplet x64-linux...
error: while detecting compiler information:
The log file content at "/src/vcpkg/buildtrees/detect_compiler/stdout-x64-linux.log" is:
CMake Error at scripts/cmake/vcpkg_execute_in_download_mode.cmake:29 (execute_process):
  execute_process failed command indexes:

    1: "Child return code: 1"

Call Stack (most recent call first):
  scripts/cmake/vcpkg_execute_in_download_mode.cmake:29 (cmake_language)
  scripts/cmake/vcpkg_find_acquire_program.cmake:110 (vcpkg_execute_in_download_mode)
  scripts/cmake/vcpkg_find_acquire_program(NINJA).cmake:1 (z_use_vcpkg_fetch)
  scripts/cmake/vcpkg_find_acquire_program.cmake:144 (include)
  scripts/cmake/vcpkg_configure_cmake.cmake:150 (vcpkg_find_acquire_program)
  scripts/detect_compiler/portfile.cmake:18 (vcpkg_configure_cmake)
  scripts/ports.cmake:206 (include)

I think this is happening because ninja is writing to stderr waiting to take filesystem lock, then the --x-stderr-status flag makes vcpkg return exit 1 on ANY stderr output

Environment

• OS: ubuntu:24.04
• Compiler: cmake v3.31.10, gcc 13.2.0

To Reproduce
Dockerfile:

FROM ubuntu:24.04

# Install minimal dependencies
RUN apt update && apt install -y \
    git wget build-essential curl zip unzip tar \
    nasm pkg-config python3 \
    gcc-mingw-w64-x86-64 g++-mingw-w64-x86-64

WORKDIR /src

RUN git clone https://github.com/microsoft/vcpkg vcpkg && \
    cd vcpkg && \
    git checkout e5a1490e1409d175932ef6014519e9ae149ddb7c && \
    cd ..
RUN ./vcpkg/bootstrap-vcpkg.sh

COPY vcpkg.json .

CMD ["bash"]

Manifest vcpkg.json (the particular port doesn't matter, just something that requires ninja):

{
  "$schema": "https://raw.githubusercontent.com/microsoft/vcpkg-tool/main/docs/vcpkg.schema.json",
  "dependencies": [
    {
      "name": "dav1d",
      "platform": "x64 & windows"
    }
  ],
  "builtin-baseline": "e5a1490e1409d175932ef6014519e9ae149ddb7c"
}

Build script build.ps1:

#!/usr/bin/env pwsh

$ErrorActionPreference = 'Stop'
$PSNativeCommandUseErrorActionPreference = $true

Set-Location -LiteralPath $PSScriptRoot

$container_name = "vcpkg-repro"

docker rm -f $container_name 2>$null
docker build -t vcpkg-repro .
docker run -dit --name $container_name vcpkg-repro

docker exec -it $container_name vcpkg/vcpkg install --triplet="x64-mingw-dynamic" --vcpkg-root="vcpkg" --x-manifest-root=""

Expected behavior
cmake can download and use ninja when required

Failure logs

logs.txt
stdout-x64-linux.log

Additional context
The same error does not occur with x64-linux-dynamic
This may be a duplicate of #49549, but I found that quite difficult to follow.